Apollo 11 crewmembers Neil Armstrong, Michael Collins and Buzz Aldrin reunited at an event at Washington, D.C.’s National Air and Space Museum yesterday to commemorate the 40th anniversary of the first mooning landing. Armstrong called the race to the moon “the ultimate peaceful contest,” while Aldrin and Collins spoke about their hopes for future exploration of Mars, the BBC reported.

Collins, who circled the moon in the Apollo aircraft while Armstrong and Aldrin explored it on foot, expressed his preference for Mars exploration over that of the moon. "I worry that the current emphasis on returning to the Moon will cause us to become ensnared in a technological briar patch needlessly delaying for decades the exploration of Mars—a much more worthwhile destination,” he told the BBC.

Eugene Cernan, the last astronaut to set foot on the moon, agreed with Collins’ emphasis on Mars. “The ultimate goal, truly, is to go to Mars," Cernan said.

In 2004, President George W. Bush proposed the Vision for Space Exploration project with the goal of making the moon fit for human habitation by the year 2020. This potential moon colony would then serve as a starting point for the eventual exploration of Mars, currently led by the rovers Spirit and Opportunity, which landed on Mars soil in early 2004.

In January, the Spirit rover began showing signs of deterioration, failing to record its activities or heed NASA’s remote commands. Some scientists speculated that the rover’s inexplicable behavior could be caused by cosmic rays, but others joked about Spirit entering a phase of teenage defiance.